Controller and control system that stores data in current control cycle for output in next control cycle

Abstract

A controller includes a processor and a communication circuit. The controller controls an object of control by sequentially repeating, on a predetermined control cycle, the transmission of the output data, the reception of the input data, and execution of a control program for generating the output data using the input data. In the transmission of the output data, the processor executes: storing of the output data in a frame, the output data having been generated by the execution of the control program in a previous control cycle; and control of the communication circuit such that the frame, in which the output data is stored, is transmitted to the object of control. The processor executes, in a current control cycle, at least a part of the storing of the output data in a frame that is to be executed in a next control cycle.

The invention claimed is: 
     
       1. A controller that controls an object of control, the controller comprising:
 a processor; and 
 a communication circuit that executes transmission of output data to the object of control, and reception of input data from the object of control, wherein 
 the controller controls the object of control by sequentially repeating, on a predetermined control cycle, the transmission of the output data, the reception of the input data, and execution of a control program for generating the output data using the input data, 
 in the transmission of the output data, the processor executes
 storing the output data to be included in a frame, in a transmission buffer, the output data having been generated by the execution of the control program in a previous control cycle, and 
 control of the communication circuit such that the frame including the output data, is transmitted to the object of control, and 
 
 the processor executes, in a current control cycle, at least a part of storing, in the transmission buffer, output data to be included in a frame that is to be transmitted in a next control cycle. 
 
     
     
       2. The controller according to  claim 1 , wherein the processor
 in the current control cycle, executes the storing of the output data to be included in the frame that is to be transmitted in the next control cycle, after the execution of the control program, and 
 when the next control cycle starts, executes the control of the communication circuit. 
 
     
     
       3. The controller according to  claim 1 , wherein the processor
 in the current control cycle, executes a part of the storing of the output data to be included in the frame that is to be transmitted in the next control cycle, and 
 when the next control cycle starts, sequentially executes a remaining part of the storing of the output data, and the control of the communication circuit. 
 
     
     
       4. The controller according to  claim 3 , wherein
 the storing of the output data to be included in the frame includes
 generation of the frame, and 
 storing of the output data in the generated frame, 
 
 the controller exchanges data with an other another device via a higher-level network, and 
 when the output data is updated as a result of the exchange of data with the other device after the execution of the control program in a control cycle, the processor, in the current control cycle, generates the frame that is to be transmitted in the next control cycle, after the execution of the reception of the input data and before the execution of the control program, and when the next control cycle starts, executes the storing of the output data. 
 
     
     
       5. The controller according to  claim 3 , wherein
 the storing of the output data to be included in the frame includes
 generation of the frame, and 
 storing of the output data in the generated frame, 
 
 the controller exchanges data with an other another device via a higher-level network, and 
 when the output data is updated as a result of the exchange of data with the other device after the execution of the control program in a control cycle, the processor, in the current control cycle, executes the storing of the output data that is to be included in a frame that is to be transmitted in the next control cycle, after the execution of the control program and before the execution of the exchange of data with the other device, and when the next control cycle starts, sequentially executes storing of the updated output data, the updated output data to be included in the frame, and the control of the communication circuit. 
 
     
     
       6. A control system comprising:
 a controller; and 
 one or more devices that work in accordance with a control command from the controller, wherein 
 the controller and the one or more devices have their respective timers that are time-synchronized with each other, 
 the controller including:
 a processor; and 
 a communication circuit that executes transmission of the control 
 
 command to the one or more devices, and reception of input data from the one or more devices, wherein 
 the controller controls the one or more devices by sequentially repeating, on a predetermined control cycle, the transmission of the control command, the reception of the input data, and execution of a control program for generating the control command using the input data, 
 in the transmission of the control command, the processor executes
 storing the control command to be included in a frame, in a transmission buffer, the control command having been generated by the execution of the control program in a previous control cycle, and 
 control of the communication circuit such that the frame including the control command is transmitted to the one or more devices, and 
 
 the processor executes, in a current control cycle, at least a part of storing, in the transmission buffer, as control command to be included in a frame that is to be transmitted in a next control cycle.